A scanning probe microscope (SPM) is a powerful tool which is capable of detecting and imaging surface morphology or physical quantities of a sample of interest by scanning the surface of a sample with a very fine tip (probe) and monitoring the strength of some interaction between the probe and surface. Depending upon kinds of the probe-surface interaction, SPM may be broadly divided into a scanning tunneling microscope (STM) which is based on utilization of electric current flowing between the probe and the sample, and an atomic force microscope (AFM) which is based on utilization of interatomic force acting between the probe and the sample.
FIG. 1 is a photograph showing a structure of a conventional scanning probe microscope (Model No.: XE-100, Park SYSTEMS, Korea), and FIG. 2 is a block diagram showing a structure of a scanning probe microscope.
Referring to FIGS. 1 and 2, SPM is operated by two steps for landing (bringing the subject into a measurable range) of a probe on a surface of the sample. Specifically, the probe is first rapidly brought to an approximate distance toward a sample (coarse motion), and the probe approached to the approximate distance is then accurately guided to the sample position (fine motion). For this purpose, two stages (coarse and fine) connected to the tip are typically employed. The probe landing using these coarse and fine motions may be broadly classified into two methods. One is a semi-automatic method where the coarse motion is carried out based on manipulation and experience of a user via an image information display device and the fine motion is then carried out in an automated manner. The other is an automated method where the probe is automatically driven until the desired condition is satisfied, by comparing a set point and a driving step of the probe via the use of a photo-sensitive device (PSD) in both the coarse and fine motion zones.